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1. ConcepTest 18.1 Which is the correct way to light the lightbulb with the Connect the Battery 4) all are correct 5) none are correct battery? 1) 2) 3) 2. ConcepTest 18.2 Ohm’s Law You double the voltage across 1) Ohm’s law is obeyed since the current still increases when V a certain conductor and you increases observe the current increases 2) Ohm’s law is not obeyed three times. What can you 3) This has nothing to do with Ohm’s conclude? law 3. ConcepTest 18.3a Wires I Two wires, A and B, are made of the 1) dA = 4 dB same metal and have equal length, 2) dA = 2 dB but the resistance of wire A is four times the resistance of wire B. How do their diameters compare? 3) dA = dB 4) dA = 1/2 dB 5) dA = 1/4 dB 5. ConcepTest 18.3b Wires II A wire of resistance R is 1) it decreases by a factor 4 stretched uniformly (keeping its 2) it decreases by a factor 2 volume constant) until it is twice 3) it stays the same its original length. What happens 4) it increases by a factor 2 to the resistance? 5) it increases by a factor 4 5. ConcepTest 18.4 Dimmer 1) the power When you rotate the knob of a 2) the current light dimmer, what is being 3) the voltage changed in the electric circuit? 4) both (1) and (2) 5) both (2) and (3) 6. ConcepTest 18.5a Lightbulbs Two lightbulbs operate at 120 V, but 1) the 25 W bulb one has a power rating of 25 W while 2) the 100 W bulb the other has a power rating of 100 W. 3) both have the same Which one has the greater 4) this has nothing to do with resistance resistance? 7. ConcepTest 18.5b Space Heaters I Two space heaters in your living room are operated at 120 V. 1) heater 1 Heater 1 has twice the resistance 2) heater 2 of heater 2. Which one will give 3) both equally off more heat?